RigidBody,velocity not working on Start method

Hi everyone,

I am pretty noob in Unity but i am having some trouble that i don´t understand. I saw some tutorials where they assign a initial velocity to a rigidbody, and i am doing the exactly same thing and it´s not working. They do it in the Start() method but for me only works on the Update method. This is really a problem for me because i need it on the Start method in order to not assinging the same velocity in every frame.

Like this doesnt work:

 public class testVelocity : MonoBehaviour {
     public Vector3 initialVelocity;
     public Vector3 initialAngularVelocity;
 
     private Rigidbody rigidBodyBall;
     // Use this for initialization
     void Start () {
         rigidBodyBall = GetComponent<Rigidbody>();
         rigidBodyBall.velocity = initialVelocity;
         rigidBodyBall.angularVelocity = initialAngularVelocity;
     }
     
     // Update is called once per frame
     void Update () {
         
     }
 }

It only works like here:

 public class testVelocity : MonoBehaviour {
     public Vector3 initialVelocity;
     public Vector3 initialAngularVelocity;
 
     private Rigidbody rigidBodyBall;
     // Use this for initialization
     void Start () {
         rigidBodyBall = GetComponent<Rigidbody>();
         
     }
     
     // Update is called once per frame
     void Update () {
         rigidBodyBall.velocity = initialVelocity;
         rigidBodyBall.angularVelocity = initialAngularVelocity;
     }
 }